1. Field of the Invention
This invention relates to high speed writing equipment and more particularly to ink supplies for such equipment.
2. Prior Art
The invention disclosed herein is directed to the provision of an ink supply for ink writing systems wherein the ink supply is exchangeable within the mechanism to allow ease of replenishment of ink for the writing mechanism. The supply includes an ink bag or chamber which has a flexible wall portion. The chamber is sealed and has a dispensing opening sealed with an elastomeric member which can be pierced by a hollow needle to draw off ink from within the chamber.
High speed ink writing devices presently in use or contemplated include, among other types, those having writing head carriages which are moved longitudinally past a record carrier on which a record is to be made. The writing head attached to the carriage is supplied with writing liquid to be applied to the record carrier which may be a sheet of paper. The writing liquid, normally ink, is supplied to the writing head through a supply system from a supply bottle.
In a known type of writing head, the head includes an ink dispensing portion which consists of a mosaic of ink jets having open dispensing orifice ends located at a face of the writing head. The ink jets may be piezo-electrically driven to squirt or eject ink from the opening across a small gap or air space onto the recording carrier. Activation of the individual jets is controlled from a writing head control center which forms no part of this invention. It is common in such devices that the individual piezo-electrically driven nozzles are quite small in diameter and it is known to have them dimensioned with respect to the liquid being used so that they are self filling with ink as a result of capillary action. Thus during the writing process ink will be constantly drawn into the writing head.
Due to the physical principles involved in supplying the ink and in squirting the ink onto the recording carrier, it is critically important to prevent air entry and entrapment within the supply system. When the writing system is put into operation initially, and importantly, when the ink supply container is changed, it is necessary to insure that the entire ink system is filled with ink.
In order to insure that the entire ink supply system, including the individual jets themselves, are properly filled with ink, it has been known to apply an overpressure on the ink supply for a short period of time. This overpressure causes a positive ink flow through the writing head thus flushing the entire supply system and the writing head with the ink. This assures that there is no trapped air present in the system.
Flushing also has the highly desirable effect of insuring that any dirt or any other contaminants which might possibly have entered the system will also be flushed out.
A typical type of ink container known to the art comprises a flexible ink bag which is supplied with ink for the writing head. The ink bag has a casing which is provided with ink passage openings extending in a vertical direction within the ink bag and forming exit channels for the ink. The ink passage openings both seal the ink bag and provide a connection to a hollow needle connecting the ink bag with the supply line of the writing head. This type of sealing allows the use of a sealed system.
It would be an improvement in the art to provide ink supply systems which have the sealing advantages discussed above, which are capable of being used in the flushing manner discussed above but which are easily removed from the writing system and easily replaced. It would also be an advance in the art to provide such systems with convenient means for disposing of the waste ink generated by the flushing process.